Quantum dot light emitting diode, manufacturing method thereof and display panel

ABSTRACT

The present disclosure provides a quantum dot light emitting diode, including: a first electrode, a second electrode, a quantum dot light emitting layer between the first electrode and the second electrode, at least one electron transport layer between the quantum dot light emitting layer and the first electrode, and an electron contribution layer between the electron transport layer of the at least one electron transport layer closest to the first electrode and the quantum dot light emitting layer; a material of the electron contribution layer includes a metal material. The embodiment of the present disclosure also provides a method for manufacturing the quantum dot light emitting diode and a display panel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the priority of the Chinese PatentApplication No. 202011110885.2 filed on Oct. 16, 2020, the content ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of display technology, andin particular to a quantum dot light emitting diode, a manufacturingmethod thereof and a display panel.

BACKGROUND

A quantum dot light emitting diode (QLED) generally includes a lightemitting layer having a plurality of quantum dot nanocrystals andsandwiched between an electron transport layer and a hole transportlayer. An electric field is applied to the quantum dot light emittingdiode, causing electrons and holes to move into the light emitting layerwhere they are trapped in the quantum dots and recombined with eachother, for emitting photons. Compared with an organic light emittingdiode, the quantum dot light emitting diode has a narrower emissionspectrum.

SUMMARY

The present disclosure provides a quantum dot light emitting diode, amanufacturing method thereof and a display panel.

In a first aspect, the embodiment of the present disclosure provides aquantum dot light emitting diode, including: a first electrode, a secondelectrode, a quantum dot light emitting layer between the firstelectrode and the second electrode, at least one electron transportlayer between the quantum dot light emitting layer and the firstelectrode, and an electron contribution layer between an electrontransport layer of the at least one electron transport layer closest tothe first electrode and the quantum dot light emitting layer; a materialof the electron contribution layer includes a metal material.

In some embodiments, a work function of the metal material is less than4 eV.

In some embodiments, the metal material includes: at least one ofmagnesium, lithium and cesium.

In some embodiments, a thickness of the electron contribution layer isin a range of 1 nm to 100 nm.

In some embodiments, the at least one electron transport layer comprisesone electron transport layer, the electron contribution layer is betweenthe electron transport layer and the quantum dot light emitting layer.

In some embodiments, the at least one electron transport layer comprisesa plurality of electron transport layers, the electron contributionlayer is between any two adjacent electron transport layers in theplurality of electron transport layers.

In some embodiments, a material of the quantum dot light emitting layerincludes: at least one of indium phosphide quantum dots or indiumphosphide derived quantum dots having a core-shell structure, blue lightcadmium-containing quantum dots, GaP/ZnSe, CsPbBr₃/ZnS; a material ofthe electron transport layer includes: at least one of zinc oxide,magnesium zinc oxide, aluminum zinc oxide and magnesium aluminum zincoxide.

In some embodiments, the quantum dot light emitting diode furtherincludes a hole transport layer and a hole injection layer; the holetransport layer is between the second electrode and the quantum dotlight emitting layer, and the hole injection layer is between the secondelectrode and the hole transport layer.

In a second aspect, the embodiment of the present disclosure furtherprovide a display panel, including: a quantum dot light emitting diodeas described herein or manufactured according to the methods describedherein.

In a third aspect, the embodiment of the present disclosure furtherprovide a method for manufacturing a quantum dot light emitting diode,including steps of: forming a first electrode, a second electrode, aquantum dot light emitting layer between the first electrode and thesecond electrode, at least one electron transport layer between thequantum dot light emitting layer and the first electrode, and anelectron contribution layer between an electron transport layer of theat least one electron transport layer closest to the first electrode andthe quantum dot light emitting layer; wherein a material of the electroncontribution layer includes a metal material.

In some embodiments, the at least one electron transport layer comprisesone electron transport layer; the step of forming the first electrode,the second electrode, the quantum dot light emitting layer, the at leastone electron transport layer, and the electron contribution layerincludes steps of: forming the first electrode on a substrate; formingthe electron transport layer on a side of the first electrode distal tothe substrate; forming the electron contribution layer on a side of theelectron transport layer distal to the first electrode; forming thequantum dot light emitting layer on a side of the electron contributionlayer distal to the electron transport layer; forming the secondelectrode on a side of the quantum dot light emitting layer distal tothe electron contribution layer.

In some embodiments, the at least one electron transport layer comprisesone electron transport layer; the step of forming the first electrode,the second electrode, the quantum dot light emitting layer, the at leastone electron transport layer, and the electron contribution layerincludes steps of: forming the second electrode on a substrate; formingthe quantum dot light emitting layer on a side of the second electrodedistal to the substrate; forming the electron contribution layer on aside of the quantum dot light emitting layer distal to the secondelectrode; forming the electron transport layer on a side of theelectron contribution layer distal to the quantum dot light emittinglayer; forming the first electrode on a side of the electron transportlayer distal to the electron contribution layer.

In some embodiments, the at least one electron transport layer includesa first electron transport layer and a second electron transport layer,the first electron transport layer is closer to the first electrode thanthe second electron transport layer; the step of forming the firstelectrode, the second electrode, the quantum dot light emitting layer,the at least one electron transport layer, and the electron contributionlayer includes steps of: forming the first electrode on a substrate;forming the first electron transport layer on a side of the firstelectrode distal to the substrate; forming the electron contributionlayer on a side of the first electron transport layer distal to thefirst electrode; forming the second electron transport layer on a sideof the electron contribution layer distal to the first electrontransport layer; forming the quantum dot light emitting layer on a sideof the second electron transport layer distal to the electroncontribution layer; forming the second electrode on a side of thequantum dot light emitting layer distal to the second electron transportlayer.

In some embodiments, the at least one electron transport layer includesa first electron transport layer and a second electron transport layer,the first electron transport layer is closer to the first electrode thanthe second electron transport layer; the step of forming the firstelectrode, the second electrode, the quantum dot light emitting layer,the at least one electron transport layer, and the electron contributionlayer includes steps of: forming the second electrode on a substrate;forming the quantum dot light emitting layer on a side of the secondelectrode distal to the substrate; forming the second electron transportlayer on a side of the quantum dot light emitting layer distal to thesecond electrode; forming the electron contribution layer on a side ofthe second electron transport layer distal to the quantum dot lightemitting layer; forming the first electron transport layer on a side ofthe electron contribution layer distal to the second electron transportlayer; forming the first electrode on a side of the first electrontransport layer distal to the electron contribution layer.

In some embodiments, a work function of the metal material is less than4 eV.

In some embodiments, a thickness of the electron contribution layer isin a range of 1 nm to 100 nm.

In some embodiments, a material of the quantum dot light emitting layerincludes: at least one of indium phosphide quantum dots or indiumphosphide derived quantum dots having a core-shell structure, blue lightcadmium-containing quantum dots, GaP/ZnSe, CsPbBr₃/ZnS; a material ofthe electron transport layer includes: at least one of zinc oxide,magnesium zinc oxide, aluminum zinc oxide and magnesium aluminum zincoxide.

In some embodiments, the metal material includes: at least one ofmagnesium, lithium and cesium.

BRIEF DESCRIPTION OF DRAWINGS

Drawings are included to provide a further understanding of someembodiments of the present disclosure, constitute a part of thespecification, and explain the present disclosure together with someembodiments of the present disclosure, but do not limit the presentdisclosure. The above and other features and advantages will become moreapparent to one of ordinary skill in the art by describing in detailexemplary embodiments with reference to the drawings, in which:

FIG. 1 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram illustrating energy levels and an electroncontribution principle of layers in a quantum dot light emitting diodeaccording to an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a quantum dot light emittingdiode according to the embodiment of the present disclosure;

FIG. 5 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure;

FIG. 6 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure;

FIGS. 7a to 7e are schematic diagrams of structures at various processesof the method for manufacturing a quantum dot light emitting diode shownin FIG. 6;

FIG. 8 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure;

FIG. 9 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure; and

FIG. 10 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure.

DETAIL DESCRIPTION OF EMBODIMENTS

In order to make one of ordinary skill in the art better understand thetechnical solution of the present disclosure, a quantum dot lightemitting diode, a manufacturing method thereof, a display panel, and adisplay device provided in the present disclosure are described indetail below with reference to the drawings.

Some embodiments of the present disclosure will be described more fullyhereinafter with reference to the drawings, but the embodiments shownmay be embodied in different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the present disclosure to one of ordinaryskill in the art.

Some embodiments of the present disclosure may be described withreference to plan and/or cross-sectional views by way of idealizedschematic illustrations of the present disclosure. Accordingly, theexample illustrations may be modified in accordance with manufacturingtechniques and/or tolerances.

Embodiments of the present disclosure and features of the embodimentsmay be combined with each other without conflict.

The terms used in the present disclosure are only used for describingparticular embodiments and are not intended to limit the presentdisclosure. As used in this disclosure, the term “and/or” includes anyand all combinations of one or more associated listed items. As used inthis disclosure, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “including”, “comprising”, “made of”, as used inthis disclosure, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used in this disclosure have the same meaning as commonlyunderstood by one of ordinary skill in the art. It will be furtherunderstood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense, unless expressly so defined herein.

Some embodiments of the present disclosure are not limited to theembodiments shown in the drawings, but include modifications ofconfigurations formed based on manufacturing processes. Thus, regionsillustrated in the drawings have schematic properties, and their shapesillustrate specific shapes of regions of elements, but are not intendedto be limiting.

In general, a basic structure of a light emitting device includes: ananode, a cathode, and a light emitting layer between the anode and thecathode. Under the action of an applied voltage, electrons and holes areinjected from the cathode and the anode, respectively, then migrate, andmeet and recombine in the light emitting layer, thereby generatingexcitons. The energy of the excitons is attenuated in the form of light,that is, the light is radiated. When the light emitting device is aquantum dot light emitting diode, the light emitting layer is a quantumdot light emitting layer; the quantum dot light emitting layer is madeof a quantum dot material as the name implies.

The light emitting device may be a normal structured light emittingdevice or an inverted structured light emitting device. The lightemitting device generally includes a substrate. In the case of thenormal structured light emitting device, an anode is closer to thesubstrate than a cathode. In the case of the inverted structured lightemitting device, a cathode is closer to the substrate than an anode.Whether the light emitting device is the normal structured lightemitting device or the inverted structured light emitting device, thelight emitting device may be a top emission light emitting device or abottom emission light emitting device. When the light emitting device isa normal structured top emission light emitting device, an anode is areflective electrode and a cathode is a transmissive electrode; when thelight emitting device is a normal structured bottom emission lightemitting device, an anode is a transmissive electrode and a cathode is areflective electrode; when the light emitting device is an invertedstructured top emission light emitting device, an anode is atransmissive electrode and a cathode is a reflective electrode; when thelight emitting device is an inverted structured bottom emission lightemitting device, an anode is a reflective electrode and a cathode is atransmissive electrode.

With the continuous optimization of performances of the light emittingdevice, the light emitting device not only includes the anode, thecathode and the light emitting layer; a hole injection layer (HIL), ahole transport layer (HTL), and an electron transport layer (ETL) may bedisposed between the anode and the light emitting layer. Further, anelectron injection layer (EIL) may be further disposed between theelectron transport layer and the cathode.

At present, a cadmium-free (Cd-free) quantum dot material or a bluelight cadmium-containing quantum dot material is generally used as thequantum dot light emitting layer. In practical applications and tests,in the quantum dot light emitting diode in which the cadmium-freequantum dot material or the blue light cadmium-containing quantum dotmaterial is used as the quantum dot light emitting layer, the problem,that the light emitting efficiency of the device is low due tounbalanced carrier transmission, exists. The main reasons are in that anelectron injection rate of the quantum dot light emitting layer issmaller than a hole injection rate, causing unbalanced carrierinjection, so that holes are excessively accumulated in the quantum dotlight emitting layer, causing the charging quantum dot light emittinglayer in the device, which adversely affects the service life and thelight emitting efficiency of the quantum dot light emitting diode.

In order to solve the above technical problem, the embodiments of thepresent disclosure provide a quantum dot light emitting diode, amanufacturing method thereof, a display panel, and a display device.

FIG. 1 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure. As shown inFIG. 1, the quantum dot light emitting diode includes: a first electrode1, a second electrode 2, a quantum dot light emitting layer 3, at leastone electron transport layer 4 and an electron contribution (supply)layer 5. The quantum dot light emitting layer 3 is arranged between thefirst electrode 1 and the second electrode 2, the at least one electrontransport layer 4 is arranged between the quantum dot light emittinglayer 3 and the first electrode 1, and the electron contribution layer 5is arranged between an electron transport layer 4 of the at least oneelectron transport layer 4 closest to the first electrode 1 and thequantum dot light emitting layer 3.

A material of the electron contribution layer 5 includes a metalmaterial, and is configured to inject free electrons on a surface of theelectron contribution layer 5 into the quantum dot light emitting layer3 under the action of an electric field between the first electrode 1and the second electrode 2.

In the embodiment of the present disclosure, the first electrode 1serves as a cathode and the second electrode 2 serves as an anode.

In the embodiment of the present disclosure, during the operation of thequantum dot light emitting diode, different voltages are applied on thefirst electrode 1 and the second electrode 2 (the voltage applied on thesecond electrode 2 is greater than that on the first electrode 1), sothat an electric field is formed between the first electrode 1 and thesecond electrode 2, and has a direction from the second electrode 2 tothe first electrode 1. Since the metal material in the electroncontribution layer 5 contains a large amount of free electrons, whichmove to the quantum dot light emitting layer 3 under the action of theelectric field between the first electrode 1 and the second electrode 2,the number of electrons injected into the quantum dot light emittinglayer 3 per unit time is increased (the electron contribution layer 5partially contributes to electron injection). After the free electronsin the metal material in the electron contribution layer 5 are reduced,the metal material with reduced electrons attracts the electrons in thefirst electrode 1, so that the electrons are continuously injected fromthe first electrode 1 to the electron contribution layer 5. Based on theprocess, an electron transport rate between the first electrode 1 andthe quantum dot light emitting layer 3 is increased, and electronsinjected into the quantum dot light emitting layer 3 per unit time areincreased, so that the unbalanced injection between holes and electronsat the quantum dot light emitting layer 3 is favorably alleviated oreven eliminated, and thus, the service life and the light emittingefficiency of the quantum dot light emitting diode may be improved.

In some embodiments, a material of the quantum dot light emitting layer3 may be InP (indium phosphide) quantum dots or indium phosphide derivedquantum dots having a core-shell structure, such as InP/ZnSe/ZnS,InP/ZnSeS/ZnS; also may be blue light cadmium-containing quantum dotssuch as CdS/ZnSe/ZnS, CdSe/ZnSe/ZnS, CdSInS/ZnSe/ZnS; and also may bequantum dots, such as GaP/ZnSe, CsPbBr₃/ZnS.

In some embodiments, a material of the electron transport layer 4includes: at least one of zinc oxide (ZnO), magnesium zinc oxide,aluminum zinc oxide, and magnesium aluminum zinc oxide.

In some embodiments, a work function of the metal material is less than4.0 eV. The smaller the work function of the metal material is, the moreeasily electrons escape from metal atoms, to form free electrons. Thatis, the more free electrons in the metal material are, the moreelectrons injected from the electron contribution layer 5 to the quantumdot light emitting layer 3 are. Therefore, in the embodiment of thepresent disclosure, the electron contribution layer 5 may be made of ametal material having a low work function.

In some embodiments, the metal material includes: at least one ofmagnesium (Mg), lithium (Li), cesium (Cs); where the work function WFfor Mg is about 3.66 eV, for Li is about 2.9 eV, and for Cs is about2.14 eV.

In the embodiment of the present disclosure, a thickness and a positionof the electron contribution layer 5 also have an effect on the numberof electrons injected from the electron contribution layer 5 to thequantum dot light emitting layer 3.

In some embodiments, where the material and the position of electroncontribution layer 5 are known, the greater the thickness of electroncontribution layer 5 is, the more free electrons in electroncontribution layer 5 are, the greater the number of electrons that maybe injected to quantum dot light emitting layer 3 per unit time is;conversely, the smaller the thickness of the electron contribution layer5 is, the less free electrons in the electron contribution layer 5 are,and the smaller the number of electrons that may be injected into thequantum dot light emitting layer 3 per unit time is. Therefore, theelectron transport rate between the first electrode 1 and the quantumdot light emitting layer 3 may be controlled by adjusting the thicknessof the electron contribution layer 5, and thus, the number of electronsinjected into the quantum dot light emitting layer 3 per unit time iscontrolled, so as to achieve the purpose of alleviating or eveneliminating the unbalanced injection between holes and electrons at thequantum dot light emitting layer 3. In some embodiments, the thicknessof the electron contribution layer 5 may be in the range of 1 nm to 100nm, wherein the thickness of the electron contribution layer 5 may be 1nm or 100 nm.

When the quantum dot light emitting diode is a normal structured topemission quantum dot light emitting diode or an inverted structuredbottom emission quantum dot light emitting diode (a side where the firstelectrode 1 is provided is the light outgoing side), the thickness ofthe electron contribution layer 5 affects the light emitting efficiencyof the quantum dot light emitting diode. The greater the thickness ofthe electron contribution layer 5 is, the lower the light transmittancethereof is, and the lower the light emitting efficiency of the quantumdot light emitting diode is. Considering these factors, such as theamount of electrons injected by the electron contribution layer 5 andthe light emitting efficiency of the quantum dot light emitting diode,in some embodiments, the thickness of the electron contribution layer 5may be in the range of 1 nm to 10 nm, wherein the thickness of theelectron contribution layer 5 may be 1 nm or 10 nm.

In the case where the material and the thickness of the electroncontribution layer 5 are known, the greater a distance between theelectron contribution layer 5 and the quantum dot light emitting layer 3is, the greater a distance, by which the electrons in the electroncontribution layer 5 move to the quantum dot light emitting layer 3, is,the greater the probability, that the electrons collide with other atomsduring the movement, is. Since the kinetic energy of the electrons isreduced after the collision occurs, the number of electrons which cannotreach the quantum dot light emitting layer 3 is increased, so that thenumber of electrons which may be actually injected into the quantum dotlight emitting layer 3 per unit time is reduced. Conversely, the smallera distance between the electron contribution layer 5 and the quantum dotlight emitting layer 3 is, the smaller a distance, by which theelectrons in the electron contribution layer 5 move to the quantum dotlight emitting layer 3, is, the smaller the probability, that theelectrons collide with other atoms during the movement, is. Therefore,the number of electrons with the kinetic energy reduced after thecollision occurs is reduced, the number of electrons which may reach thequantum dot light emitting layer 3 is increased, so that the number ofelectrons which may be injected into the quantum dot light emittinglayer 3 per unit time is reduced. Therefore, by adjusting the distancebetween the electron contribution layer 5 and the quantum dot lightemitting layer 3, the number of electrons injected into the quantum dotlight emitting layer 3 per unit time may be controlled, so as to achievethe purpose of alleviating or even eliminating the unbalanced injectionbetween holes and electrons at the quantum dot light emitting layer 3.

In some embodiments, as shown in FIG. 1, the quantum dot light emittingdiode further includes a hole transport layer 7 located between thesecond electrode 2 and the quantum dot light emitting layer 3, and ahole injection layer 8 located between the second electrode 2 and thehole transport layer 7.

In some embodiments, a material of the hole injection layer 8 includes,but is not limited to, poly (3,4-ethylenedioxythiophene monomer)polystyrene sulfonate (PEDOT: PSS), polythiophene, polyaniline,polypyrrole, copper phthalocyanine.

In some embodiments, a material of the hole transport layer 7 includes,but is not limited to, p-type polymer materials and various p-typematerials having a low molecular weight, such as, polythiophene,polyaniline, polypyrrole, a mixture havingpoly-3,4-ethylenedioxythiophene and poly (sodium p-styrenesulfonate),4,4′-cyclohexylidene bis [N, N-bis (4-methylphenyl) aniline] (TAPC), or4,4′,4″-tris (N-carbazolyl) triphenylamine (TCTA), N, N′-bis(1-naphthyl)-N, N′-diphenylbenzidine (NPB).

In some embodiments, an electron injection layer (not shown) is furtherdisposed between the electron transport layer 4 and the first electrode1; a material of the electron injection layer includes, but is notlimited to, any one of lithium fluoride, sodium fluoride, potassiumfluoride, rubidium fluoride, cesium fluoride, lithium oxide, and lithiummetaborate.

It should be noted that only one electron transport layer 4 isexemplarily shown in FIG. 1, and the electron contribution layer 5 islocated between the electron transport layer 4 and the quantum dot lightemitting layer 3 and is in contact with the quantum dot light emittinglayer 3, which only serves as an exemplary function and does not limitthe technical solution of the present disclosure.

With continued reference to FIG. 1, the quantum dot light emitting diodeshown in FIG. 1 further includes a substrate 6 located on a side of thesecond electrode 2 distal to the first electrode 1, therefore, such aquantum dot light emitting diode is a normal structured quantum dotlight emitting diode.

FIG. 2 is a schematic diagram illustrating energy levels of layers andthe electron contribution principle in a quantum dot light emittingdiode according to an embodiment of the present disclosure. As aspecific example, as shown in FIG. 2, the material of the firstelectrode 1 is aluminum, and a fermi level of the aluminum is about −4.3eV; the electron transport layer 4 is made of magnesium zinc oxide, andenergy levels of the magnesium zinc oxide are as follows: a valence bandbeing about −7.3 eV and a conduction band being about −3.7 eV; thematerial of the electron contribution layer 5 is magnesium, and aconduction band of the magnesium is about −3.66 eV (a work function isabout 3.66 eV); the quantum dot light emitting layer 3 is made ofInP/ZnSeS/ZnS, and the InP/ZnSeS/ZnS has energy levels as follows: avalence band being about −5.9 eV and a conduction band being about −3.5eV; the hole transport layer 7 is made of poly (9,9-dioctylfluorene-CO—N-(4-butyl phenyl) diphenylamine) (TFB), and energy levelsof the TFB are as follows: a valence band being about-5.3 eV and aconduction band being about −2.3 eV; the material of the hole transportlayer 7 is PEDOT: PSS, energy levels of PEDOT: PSS are as follows: avalence band being about −5.0 eV and a conduction band being about −3.5eV; the second electrode 2 is made of Indium Tin Oxide (ITO) with afermi level of about −4.7 eV.

When the quantum dot light emitting diode operates, the direction of theelectric field points to the first electrode 1 from the second electrode2, and the electron contribution layer 5 injects free electrons to thequantum dot light emitting layer 3.

FIG. 3 is a schematic structural diagram of a quantum dot light emittingdiode provided in an embodiment of the present disclosure. As shown inFIG. 3, unlike the quantum dot light emitting diode shown in FIG. 1, thesubstrate 6 shown in FIG. 3 is located on a side of the first electrode1 distal to the second electrode 2, and thus, the quantum dot lightemitting diode is an inverted structured quantum dot light emittingdiode.

In some embodiments of the present disclosure, the at least one electrontransport layer 4 is a plurality of electron transport layers, and theelectron contribution layer 5 is located between any two adjacentelectron transport layers in the plurality of electron transport layers.The following description will be given by taking as an example that theat least one electron transport layer 4 includes an electron transportlayer 4 a and an electron transport layer 4 b.

FIG. 4 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure. As shown inFIG. 4, unlike the quantum dot light emitting diodes shown in FIGS. 1and 3, the quantum dot light emitting diode shown in FIG. 4 includes twoelectron transport layers 4 a and 4 b, and the electron contributionlayer 5 is located between the two electron transport layers 4 a and 4b.

For convenience of description, the two electron transport layers 4 a, 4b are referred to as a first electron transport layer 4 a and a secondelectron transport layer 4 b, respectively, and the first electrontransport layer 4 a is closer to the first electrode 1 than the secondelectron transport layer 4 b. The second electron transport layer 4 b islocated between the quantum dot light emitting layer 3 and the electroncontribution layer 5, so that by controlling a thickness of the secondelectron transport layer 4 b, the distance between the electroncontribution layer 5 and the quantum dot light emitting layer 3 may becontrolled that is, the number of free electrons injected into thequantum dot light emitting layer 3 from the electron contribution layer5 is controlled, so as to control the electron transport rate betweenthe first electrode 1 and the quantum dot light emitting layer 3.

It should be noted that, in the embodiment of the present disclosure,materials of the first electron transport layer 4 a and the secondelectron transport layer 4 b may be the same or different; thicknessesof the first electron transport layer 4 a and the second electrontransport layer 4 b may be the same or different.

The substrate 6 in FIG. 4 is located on a side of the second electrode 2distal to the first electrode 1, and thus, the quantum dot lightemitting diode is a normal structured quantum dot light emitting diode.

FIG. 5 is a schematic structural diagram of a quantum dot light emittingdiode according to an embodiment of the present disclosure. As shown inFIG. 5, unlike the quantum dot light emitting diode shown in FIG. 4, thesubstrate 6 shown in FIG. 5 is located on a side of the first electrode1 distal to the second electrode 2, and thus, the quantum dot lightemitting diode is an inverted structured quantum dot light emittingdiode.

Alternatively, the number of the electron transport layers in theembodiment of the present disclosure may also be three or more, thematerial and the thickness of each electron transport layer are notlimited, and it is only necessary to ensure that the electroncontribution layer 5 is disposed between the electron transport layerclosest to the first electrode 1 and the quantum dot light emittinglayer 3, and specific cases are not described herein.

In some embodiments, the hole injection layer, the hole transport layerin FIGS. 1, 3, 4 and 5 may be removed.

In the embodiment of the present disclosure, the electron contributionlayer is provided, free electrons of the metal material in the electroncontribution layer may be injected into the quantum dot light emittinglayer under the action of the electric field, so that an electrontransport rate between the first electrode and the quantum dot lightemitting layer is increased, and electrons injected into the quantum dotlight emitting layer per unit time are increased, the electron injectionper unit time at the quantum dot light emitting layer is increased, sothat the unbalanced injection between holes and electrons at the quantumdot light emitting layer is favorably alleviated or even eliminated, andthus, the service life and the light emitting efficiency of the quantumdot light emitting diode may be improved.

The embodiment of the present disclosure further provides a method formanufacturing the quantum dot light emitting diode, which is used formanufacturing the quantum dot light emitting diode provided by any oneof the embodiments. The manufacturing method includes: forming a firstelectrode, a second electrode, a quantum dot light emitting layer, atleast one electron transport layer and an electron contribution layer,wherein the quantum dot light emitting layer is arranged between thefirst electrode and the second electrode, the at least one electrontransport layer is arranged between the quantum dot light emitting layerand the first electrode, and the electron contribution layer is arrangedbetween an electron transport layer closest to the first electrode andthe quantum dot light emitting layer; wherein a material of the electroncontribution layer includes a metal material, and the electroncontribution layer is configured to inject free electrons on a metalsurface to the quantum dot light emitting layer under the action of anelectric field between the first electrode and the second electrode.

In the embodiment of the present disclosure, the electron contributionlayer is provided, free electrons of the metal material in the electroncontribution layer may be injected into the quantum dot light emittinglayer under the action of the electric field, so that an electrontransport rate between the first electrode and the quantum dot lightemitting layer is increased, and electrons injected into the quantum dotlight emitting layer per unit time are increased, the electron injectionper unit time at the quantum dot light emitting layer is increased, sothat the unbalanced injection between holes and electrons at the quantumdot light emitting layer is favorably alleviated or even eliminated, andthus, the service life and the light emitting efficiency of the quantumdot light emitting diode may be improved.

FIG. 6 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure.FIGS. 7a to 7e are schematic diagrams of structures at various processesof the method for manufacturing a quantum dot light emitting diode shownin FIG. 6. As shown in FIGS. 6 to 7 e, the manufacturing method may beused for manufacturing the quantum dot light emitting diode shown inFIG. 1, and specifically includes the following steps:

S101, forming a second electrode on a substrate.

Referring to FIG. 7a , in step S101, a thin layer of a conductivematerial (e.g., a thin film of an Indium Tin Oxide (ITO) material) isformed on the substrate, and then, is patterned, to form a pattern ofthe second electrode.

S102, sequentially forming a hole injection layer and a hole transportlayer on a side of the second electrode distal to the substrate.

Referring to FIG. 7b , firstly, the hole injection layer is formed on aside of the second electrode distal to the substrate, and then, the holetransport layer is formed on a side of the hole injection layer distalto the substrate. In some embodiments, the hole injection layer and thehole transport layer are generally made of organic polymers, and may beformed through a spin coating process.

In some embodiments, the material of the hole injection layer 8includes, but is not limited to, poly (3,4-ethylenedioxythiophenemonomer) polystyrene sulfonate (PEDOT: PSS), polythiophene, polyaniline,polypyrrole, copper phthalocyanine.

In some embodiments, a material of the hole transport layer 7 includes,but is not limited to, p-type polymer materials and various p-typematerials having a low molecular weight, such as, polythiophene,polyaniline, polypyrrole, a mixture havingpoly-3,4-ethylenedioxythiophene and poly (sodium p-styrenesulfonate),4,4′-cyclohexylidene bis [N, N-bis (4-methylphenyl) aniline] (TAPC), or4,4′,4″-tris (N-carbazolyl) triphenylamine (TCTA), N, N ‘-bis(1-naphthyl)-N, N’-diphenylbenzidine (NPB).

S103, forming a quantum dot light emitting layer on a side of the holetransport layer distal to the hole injection layer.

Referring to FIG. 7c , the quantum dot light emitting layer is formed ona side of the hole transport layer distal to the hole injection layer;the material of the quantum dot light emitting layer may be InP (indiumphosphide) quantum dots or indium phosphide derived quantum dots havinga core-shell structure, such as InP/ZnSe/ZnS, InP/ZnSeS/ZnS; also may beblue light cadmium-containing quantum dots such as CdS/ZnSe/ZnS,CdSe/ZnSe/ZnS, CdSInS/ZnSe/ZnS; and also may be quantum dots, such asGaP/ZnSe, CsPbBr₃/ZnS. In some embodiments, the quantum dot lightemitting layer may be formed through a spin coating process.

S104, forming an electron contribution layer on a side of the quantumdot light emitting layer distal to the hole transport layer.

Referring to FIG. 7d , the electron contribution layer is formed at aside of the quantum dot light emitting layer distal to the holetransport layer. In some embodiments, a work function of the metalmaterial is less than 4.0 eV. The smaller the work function of the metalmaterial is, the more easily electrons escape from metal atoms, to formfree electrons. That is, the more free electrons in the metal materialare, the more electrons injected from the electron contribution layer 5to the quantum dot light emitting layer 3 are. Therefore, in theembodiment of the present disclosure, the electron contribution layer 5may be made of a metal material having a low work function.

In some embodiments, the metal material includes: at least one ofmagnesium (Mg), lithium (Li), cesium (Cs); where the work function WFfor Mg is about 3.66 eV, for Li is about 2.9 eV, and for Cs is about2.14 eV.

In some embodiments, the electron contribution layer may be formedthrough an evaporation process.

S105, forming an electron transport layer on the side of the electroncontribution layer distal to the quantum dot light emitting layer.

As shown in FIG. 7e , the electron transport layer is formed on a sideof the electron contribution layer distal to the quantum dot lightemitting layer; wherein the material of the electron transport layerincludes: at least one of zinc oxide (ZnO), magnesium zinc oxide,aluminum zinc oxide, and magnesium aluminum zinc oxide.

In some embodiments, the electron transport layer may be formed througha physical vapor deposition (PVD) process or a solution method. As anexample, the electron transport layer may be formed through the solutionmethod and by using the zinc oxide material. Firstly, zinc acetate(approximately 95% in concentration) and ethanolamine (approximately 4%in concentration) were dissolved in 2-methoxyethanol, to form a zincacetate solution (approximately 75 mg/ml in density); then, the zincacetate solution is spin-coated on the electron contribution layer at aspeed of 2000 rpm; then, the substrate is subjected to an annealingprocess (at a temperature of approximately 180° C.), such that the zincacetate is decomposed at the high temperature to form a zinc oxide film,thereby forming the electron transport layer.

S106, forming a first electrode on one side of the electron transportlayer distal to the electron contribution layer.

Referring to FIG. 1, the first electrode is formed on a side of theelectron transport layer distal to the electron contribution layer; thematerial of the first electrode may be a metal material, such asaluminum or an aluminum magnesium alloy. The first electrode may beformed through an evaporation process. In some embodiments of thepresent disclosure, a thickness of the first electrode is in the rangeof 500 nm to 1000 nm, wherein the thickness of the first electrode maybe 500 nm or 1000 nm.

The quantum dot light emitting diode shown in FIG. 1 may be manufacturedthrough the steps S101 to S106. In some embodiments, when the holeinjection layer and the hole transport layer are absent in the quantumdot light emitting diode, the step S103 is unnecessarily performed. Inaddition, when the electron injection layer is present in the quantumdot light emitting diode, the method further includes a step of formingthe electron injection layer between steps S105 and S106.

FIG. 8 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure. Asshown in FIG. 8, the manufacturing method may be used for manufacturingthe quantum dot light emitting diode shown in FIG. 3, and includes thefollowing steps:

S201, forming a first electrode on a substrate.

S202, forming an electron transport layer on a side of the firstelectrode distal to the substrate.

S203, forming an electron contribution layer on a side of the electrontransport layer distal to the first electrode.

S204, forming a quantum dot light emitting layer on a side of theelectron contribution layer distal to the electron transport layer.

S205, sequentially forming a hole transport layer and a hole injectionlayer on a side of the quantum dot light emitting layer distal to theelectron contribution layer.

S206, forming a second electrode on a side of the hole injection layerdistal to the hole transport layer.

The quantum dot light emitting diode shown in FIG. 3 may be manufacturedthrough the steps S201 to S206. For specific processes (e.g., method andmaterial selection) for forming the first electrode, the electrontransport layer, the electron contribution layer, the quantum dot lightemitting layer, the hole transport layer, the hole injection layer, andthe second electrode, reference may be made to corresponding contents inthe embodiment described in FIG. 7, and details are not repeated here.

FIG. 9 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure. Asshown in FIG. 9, the manufacturing method may be used to manufacture thequantum dot light emitting diode shown in FIG. 4, and not only includessteps S101 to S106 in the embodiment shown in FIG. 6, but also includesstep S103 a between step S103 and step S104, which is described indetail below. Further, in FIG. 9, step S104 is replaced with step S104a.

S103 a is forming a second electron transport layer on a side of thequantum dot light emitting layer distal to the hole transport layer.

S104 a is forming the electron contribution layer on a side of thesecond electron transport layer distal to the quantum dot light emittinglayer.

The electron transport layer may be formed through a physical vapordeposition process (PVD) or a solution method.

In the embodiment shown in FIG. 9, the electron transport layermanufactured in step S103 a is the second electron transport layer, andthe electron transport layer manufactured in step S105 is the firstelectron transport layer.

In the process of separately forming the first electron transport layerand the second electron transport layer through the solution method,thicknesses of the first electron transport layer and the secondelectron transport layer may be controlled by controlling aconcentration of the spin-coating solution and the spin-coating speed.

FIG. 10 is a flowchart of a method for manufacturing a quantum dot lightemitting diode according to an embodiment of the present disclosure. Asshown in FIG. 10, the manufacturing method may be used for manufacturingthe quantum dot light emitting diode shown in FIG. 5, and not onlyincludes steps S201 to S206 in the embodiment shown in FIG. 8, but alsoincludes step S203 a between step S203 and step S204, which is describedin detail below. Further, in FIG. 10, step S204 is replaced with stepS204 a.

S203 a is forming a second electron transport layer on a side of theelectron contribution layer distal to the first electron transportlayer.

S204 a is forming a quantum dot light emitting layer on a side of thesecond electron transport layer distal to the electron contributionlayer.

The second electron transport layer may be formed through a physicalvapor deposition process (PVD) or a solution method.

In the embodiment shown in FIG. 10, the electron transport layermanufactured in step S203 a is the second electron transport layer, andthe electron transport layer manufactured in step S202 is the firstelectron transport layer.

In the above embodiments, the method for manufacturing layers has beendescribed. However, the present disclosure is not limited thereto. Inother embodiments of the present disclosure, other processes may be usedto manufacture the above layers.

For example, in other embodiments of the present disclosure, the holeinjection layer, the quantum dot light emitting layer, the electrontransport layer, and the cathode may be manufactured using an inkjetprinting method.

In the embodiment of the present disclosure, by manufacturing theelectron contribution layer in the quantum dot light emitting diode,free electrons of the metal material in the electron contribution layermay be injected into the quantum dot light emitting layer under theaction of the electric field, so that an electron transport rate betweenthe first electrode and the quantum dot light emitting layer isincreased, and electrons injected into the quantum dot light emittinglayer per unit time are increased, the electron injection per unit timeat the quantum dot light emitting layer is increased, so that theunbalanced injection between holes and electrons at the quantum dotlight emitting layer is favorably alleviated or even eliminated, andthus, the service life and the light emitting efficiency of the quantumdot light emitting diode may be improved.

The embodiment of the present disclosure provides a display panel, whichincludes the quantum dot light emitting diode provided by any one of theforegoing embodiments, and manufactured by any one of the foregoingmanufacturing methods. For the specific description of the quantum dotlight emitting diode and the manufacturing method thereof, reference maybe made to the corresponding contents in the foregoing embodiments, anddetails are not repeated here.

The embodiment of the present disclosure provides a display device,which includes the display panel provided in the foregoing embodiment,and may be any product or component with a display function, such as atelevision, a digital camera, a mobile phone, a tablet computer, and thelike.

The display panel and the display device provided by the embodiment ofthe present disclosure include the quantum dot light emitting diodedescribed herein or manufactured by the method described herein. Bymanufacturing the electron contribution layer in the quantum dot lightemitting diode, free electrons of the metal material in the electroncontribution layer may be injected into the quantum dot light emittinglayer under the action of the electric field, so that an electrontransport rate between the first electrode and the quantum dot lightemitting layer is increased, and electrons injected into the quantum dotlight emitting layer per unit time are increased, the electron injectionper unit time at the quantum dot light emitting layer is increased, sothat the unbalanced injection between holes and electrons at the quantumdot light emitting layer is favorably alleviated or even eliminated, andthus, the service life and the light emitting efficiency of the quantumdot light emitting diode may be improved. Further, the service life ofthe display panel and the display device including the quantum dot lightemitting diode described herein or manufactured by the method describedherein in the embodiments of the present disclosure is improved.

It should be understood that the above embodiments are merely exemplaryembodiments adopted to explain the principles of the present disclosure,and the present disclosure is not limited thereto. It will be apparentto one of ordinary skill in the art that various changes andmodifications may be made therein without departing from the spirit andessence of the present disclosure, and such changes and modificationsalso fall within the scope of the present disclosure.

What is claimed is:
 1. A quantum dot light emitting diode, comprising: afirst electrode, a second electrode, a quantum dot light emitting layerbetween the first electrode and the second electrode, at least oneelectron transport layer between the quantum dot light emitting layerand the first electrode, and an electron contribution layer between anelectron transport layer of the at least one electron transport layerclosest to the first electrode and the quantum dot light emitting layer;wherein a material of the electron contribution layer comprises a metalmaterial.
 2. The quantum dot light emitting diode of claim 1, wherein awork function of the metal material is less than 4 eV.
 3. The quantumdot light emitting diode of claim 2, wherein the metal materialcomprises: at least one of magnesium, lithium and cesium.
 4. The quantumdot light emitting diode of claim 1, wherein a thickness of the electroncontribution layer is in a range of 1 nm to 100 nm.
 5. The quantum dotlight emitting diode of claim 1, wherein the at least one electrontransport layer comprises one electron transport layer, and the electroncontribution layer is between the electron transport layer and thequantum dot light emitting layer.
 6. The quantum dot light emittingdiode of claim 1, wherein the at least one electron transport layercomprises a plurality of electron transport layers, and the electroncontribution layer is between any two adjacent electron transport layersin the plurality of electron transport layers.
 7. The quantum dot lightemitting diode of claim 1, wherein a material of the quantum dot lightemitting layer comprises: at least one of indium phosphide quantum dotsor indium phosphide derived quantum dots having a core-shell structure,blue light cadmium-containing quantum dots, GaP/ZnSe, CsPbBr₃/ZnS; and amaterial of the electron transport layer comprises: at least one of zincoxide, magnesium zinc oxide, aluminum zinc oxide and magnesium aluminumzinc oxide.
 8. The quantum dot light emitting diode of claim 1, furthercomprising a hole transport layer and a hole injection layer; whereinthe hole transport layer is between the second electrode and the quantumdot light emitting layer, and the hole injection layer is between thesecond electrode and the hole transport layer.
 9. A display panel,comprising: the quantum dot light emitting diode of claim
 1. 10. Amethod for manufacturing a quantum dot light emitting diode, comprisingsteps of: forming a first electrode, a second electrode, a quantum dotlight emitting layer between the first electrode and the secondelectrode, at least one electron transport layer between the quantum dotlight emitting layer and the first electrode, and an electroncontribution layer between an electron transport layer of the at leastone electron transport layer closest to the first electrode and thequantum dot light emitting layer; wherein a material of the electroncontribution layer comprises a metal material.
 11. The method formanufacturing a quantum dot light emitting diode of claim 10, whereinthe at least one electron transport layer comprises one electrontransport layer; the step of forming the first electrode, the secondelectrode, the quantum dot light emitting layer, the at least oneelectron transport layer, and the electron contribution layer comprisessteps of: forming the first electrode on a substrate; forming theelectron transport layer on a side of the first electrode distal to thesubstrate; forming the electron contribution layer on a side of theelectron transport layer distal to the first electrode; forming thequantum dot light emitting layer on a side of the electron contributionlayer distal to the electron transport layer; and forming the secondelectrode on a side of the quantum dot light emitting layer distal tothe electron contribution layer.
 12. The method for manufacturing aquantum dot light emitting diode of claim 10, wherein the at least oneelectron transport layer comprises one electron transport layer; thestep of forming the first electrode, the second electrode, the quantumdot light emitting layer, the at least one electron transport layer, andthe electron contribution layer comprises steps of: forming the secondelectrode on a substrate; forming the quantum dot light emitting layeron a side of the second electrode distal to the substrate; forming theelectron contribution layer on a side of the quantum dot light emittinglayer distal to the second electrode; forming the electron transportlayer on a side of the electron contribution layer distal to the quantumdot light emitting layer; and forming the first electrode on a side ofthe electron transport layer distal to the electron contribution layer.13. The method for manufacturing a quantum dot light emitting diode ofclaim 10, wherein the at least one electron transport layer comprises afirst electron transport layer and a second electron transport layer,the first electron transport layer is closer to the first electrode thanthe second electron transport layer; the step of forming the firstelectrode, the second electrode, the quantum dot light emitting layer,the at least one electron transport layer, and the electron contributionlayer comprises steps of: forming the first electrode on a substrate;forming the first electron transport layer on a side of the firstelectrode distal to the substrate; forming the electron contributionlayer on a side of the first electron transport layer distal to thefirst electrode; forming the second electron transport layer on a sideof the electron contribution layer distal to the first electrontransport layer; forming the quantum dot light emitting layer on a sideof the second electron transport layer distal to the electroncontribution layer; and forming the second electrode on a side of thequantum dot light emitting layer distal to the second electron transportlayer.
 14. The method for manufacturing a quantum dot light emittingdiode of claim 10, wherein the at least one electron transport layercomprises a first electron transport layer and a second electrontransport layer, the first electron transport layer is closer to thefirst electrode than the second electron transport layer; the step offorming the first electrode, the second electrode, the quantum dot lightemitting layer, the at least one electron transport layer, and theelectron contribution layer comprises steps of: forming the secondelectrode on a substrate; forming the quantum dot light emitting layeron a side of the second electrode distal to the substrate; forming thesecond electron transport layer on a side of the quantum dot lightemitting layer distal to the second electrode; forming the electroncontribution layer on a side of the second electron transport layerdistal to the quantum dot light emitting layer; forming the firstelectron transport layer on a side of the electron contribution layerdistal to the second electron transport layer; and forming the firstelectrode on a side of the first electron transport layer distal to theelectron contribution layer.
 15. The method for manufacturing a quantumdot light emitting diode of claim 10, wherein a work function of themetal material is less than 4 eV.
 16. The method for manufacturing aquantum dot light emitting diode of claim 10, wherein a thickness of theelectron contribution layer is in a range of 1 nm to 100 nm.
 17. Themethod for manufacturing a quantum dot light emitting diode of claim 10,wherein a material of the quantum dot light emitting layer comprises: atleast one of indium phosphide quantum dots or indium phosphide derivedquantum dots having a core-shell structure, blue lightcadmium-containing quantum dots, GaP/ZnSe, and CsPbBr₃/ZnS; a materialof the electron transport layer comprises: at least one of zinc oxide,magnesium zinc oxide, aluminum zinc oxide and magnesium aluminum zincoxide.
 18. The method for manufacturing a quantum dot light emittingdiode of claim 10, wherein the metal material comprises: at least one ofmagnesium, lithium and cesium.